/*
* Copyright (c) 2006-2007 Erin Catto http:
*
* This software is provided 'as-is', without any express or implied
* warranty.  In no event will the authors be held liable for any damages
* arising from the use of this software.
* Permission is granted to anyone to use this software for any purpose,
* including commercial applications, and to alter it and redistribute it
* freely, subject to the following restrictions:
* 1. The origin of this software must not be misrepresented; you must not
* claim that you wrote the original software. If you use this software
* in a product, an acknowledgment in the product documentation would be
* appreciated but is not required.
* 2. Altered source versions must be plainly marked, and must not be
* misrepresented the original software.
* 3. This notice may not be removed or altered from any source distribution.
*
* Converted for The Render Engine v2.0
* Aug. 4, 2010 Brett Fattori
*/

Engine.include("/physics/common/b2Settings.js");
Engine.include("/physics/common/math/b2Math.js");
Engine.include("/physics/common/math/b2Vec2.js");

Engine.include("/physics/dynamics/contacts/b2ContactConstraint.js");

Engine.include("/physics/dynamics/b2World.js");


Engine.initObject("b2ContactSolver", null, function() {

   var b2ContactSolver = Base.extend({

      m_allocator: null,
      m_constraints: null,
      m_constraintCount: 0,

      constructor: function(contacts, contactCount, allocator) {
         // initialize instance variables for references
         this.m_constraints = new Array();
         //

         this.m_allocator = allocator;

         var i = 0;
         var tVec;
         var tMat;

         this.m_constraintCount = 0;
         for (i = 0; i < contactCount; ++i)
         {
            this.m_constraintCount += contacts[i].GetManifoldCount();
         }

         // fill array
         for (i = 0; i < this.m_constraintCount; i++){
            this.m_constraints[i] = new b2ContactConstraint();
         }

         var count = 0;
         for (i = 0; i < contactCount; ++i)
         {
            var contact = contacts[i];
            var b1 = contact.m_shape1.m_body;
            var b2 = contact.m_shape2.m_body;
            var manifoldCount = contact.GetManifoldCount();
            var manifolds = contact.GetManifolds();
            var friction = contact.m_friction;
            var restitution = contact.m_restitution;

            //var v1 = b1.m_linearVelocity.Copy();
            var v1X = b1.m_linearVelocity.x;
            var v1Y = b1.m_linearVelocity.y;
            //var v2 = b2.m_linearVelocity.Copy();
            var v2X = b2.m_linearVelocity.x;
            var v2Y = b2.m_linearVelocity.y;
            var w1 = b1.m_angularVelocity;
            var w2 = b2.m_angularVelocity;

            for (var j = 0; j < manifoldCount; ++j)
            {
               var manifold = manifolds[ j ];

               //b2Settings.b2Assert(manifold.pointCount > 0);

               //var normal = manifold.normal.Copy();
               var normalX = manifold.normal.x;
               var normalY = manifold.normal.y;

               //b2Settings.b2Assert(count < this.m_constraintCount);
               var c = this.m_constraints[ count ];
               c.body1 = b1;
               c.body2 = b2;
               c.manifold = manifold;
               //c.normal = normal;
               c.normal.x = normalX;
               c.normal.y = normalY;
               c.pointCount = manifold.pointCount;
               c.friction = friction;
               c.restitution = restitution;

               for (var k = 0; k < c.pointCount; ++k)
               {
                  var cp = manifold.points[ k ];
                  var ccp = c.points[ k ];

                  ccp.normalImpulse = cp.normalImpulse;
                  ccp.tangentImpulse = cp.tangentImpulse;
                  ccp.separation = cp.separation;

                  //var r1 = b2Math.SubtractVV( cp.position, b1.m_position );
                  var r1X = cp.position.x - b1.m_position.x;
                  var r1Y = cp.position.y - b1.m_position.y;
                  //var r2 = b2Math.SubtractVV( cp.position, b2.m_position );
                  var r2X = cp.position.x - b2.m_position.x;
                  var r2Y = cp.position.y - b2.m_position.y;

                  //ccp.localAnchor1 = b2Math.b2MulTMV(b1.m_R, r1);
                  tVec = ccp.localAnchor1;
                  tMat = b1.m_R;
                  tVec.x = r1X * tMat.col1.x + r1Y * tMat.col1.y;
                  tVec.y = r1X * tMat.col2.x + r1Y * tMat.col2.y;

                  //ccp.localAnchor2 = b2Math.b2MulTMV(b2.m_R, r2);
                  tVec = ccp.localAnchor2;
                  tMat = b2.m_R;
                  tVec.x = r2X * tMat.col1.x + r2Y * tMat.col1.y;
                  tVec.y = r2X * tMat.col2.x + r2Y * tMat.col2.y;

                  var r1Sqr = r1X * r1X + r1Y * r1Y;
                  var r2Sqr = r2X * r2X + r2Y * r2Y;

                  //var rn1 = b2Math.b2Dot(r1, normal);
                  var rn1 = r1X*normalX + r1Y*normalY;
                  //var rn2 = b2Math.b2Dot(r2, normal);
                  var rn2 = r2X*normalX + r2Y*normalY;
                  var kNormal = b1.m_invMass + b2.m_invMass;
                  kNormal += b1.m_invI * (r1Sqr - rn1 * rn1) + b2.m_invI * (r2Sqr - rn2 * rn2);
                  //b2Settings.b2Assert(kNormal > Number.MIN_VALUE);
                  ccp.normalMass = 1.0 / kNormal;

                  //var tangent = b2Math.b2CrossVF(normal, 1.0);
                  var tangentX = normalY
                  var tangentY = -normalX;

                  //var rt1 = b2Math.b2Dot(r1, tangent);
                  var rt1 = r1X*tangentX + r1Y*tangentY;
                  //var rt2 = b2Math.b2Dot(r2, tangent);
                  var rt2 = r2X*tangentX + r2Y*tangentY;
                  var kTangent = b1.m_invMass + b2.m_invMass;
                  kTangent += b1.m_invI * (r1Sqr - rt1 * rt1) + b2.m_invI * (r2Sqr - rt2 * rt2);
                  //b2Settings.b2Assert(kTangent > Number.MIN_VALUE);
                  ccp.tangentMass = 1.0 /  kTangent;

                  // Setup a velocity bias for restitution.
                  ccp.velocityBias = 0.0;
                  if (ccp.separation > 0.0)
                  {
                     ccp.velocityBias = -60.0 * ccp.separation;
                  }
                  //var vRel = b2Math.b2Dot(c.normal, b2Math.SubtractVV( b2Math.SubtractVV( b2Math.AddVV( v2, b2Math.b2CrossFV(w2, r2)), v1 ), b2Math.b2CrossFV(w1, r1)));
                  var tX = v2X + (-w2*r2Y) - v1X - (-w1*r1Y);
                  var tY = v2Y + (w2*r2X) - v1Y - (w1*r1X);
                  //var vRel = b2Dot(c.normal, tX/Y);
                  var vRel = c.normal.x*tX + c.normal.y*tY;
                  if (vRel < -b2Settings.b2_velocityThreshold)
                  {
                     ccp.velocityBias += -c.restitution * vRel;
                  }
               }

               ++count;
            }
         }

         //b2Settings.b2Assert(count == this.m_constraintCount);
         
      },
      
      PreSolve: function() {
         var tVec;
         var tVec2;
         var tMat;

         // Warm start.
         for (var i = 0; i < this.m_constraintCount; ++i)
         {
            var c = this.m_constraints[ i ];

            var b1 = c.body1;
            var b2 = c.body2;
            var invMass1 = b1.m_invMass;
            var invI1 = b1.m_invI;
            var invMass2 = b2.m_invMass;
            var invI2 = b2.m_invI;
            //var normal = new b2Vec2(c.normal.x, c.normal.y);
            var normalX = c.normal.x;
            var normalY = c.normal.y;
            //var tangent = b2Math.b2CrossVF(normal, 1.0);
            var tangentX = normalY;
            var tangentY = -normalX;

            var j = 0;
            var tCount = 0;
            if (b2World.s_enableWarmStarting)
            {
               tCount = c.pointCount;
               for (j = 0; j < tCount; ++j)
               {
                  var ccp = c.points[ j ];
                  //var P = b2Math.AddVV( b2Math.MulFV(ccp.normalImpulse, normal), b2Math.MulFV(ccp.tangentImpulse, tangent));
                  var PX = ccp.normalImpulse*normalX + ccp.tangentImpulse*tangentX;
                  var PY = ccp.normalImpulse*normalY + ccp.tangentImpulse*tangentY;

                  //var r1 = b2Math.b2MulMV(b1.m_R, ccp.localAnchor1);
                  tMat = b1.m_R;
                  tVec = ccp.localAnchor1;
                  var r1X = tMat.col1.x * tVec.x + tMat.col2.x * tVec.y;
                  var r1Y = tMat.col1.y * tVec.x + tMat.col2.y * tVec.y;

                  //var r2 = b2Math.b2MulMV(b2.m_R, ccp.localAnchor2);
                  tMat = b2.m_R;
                  tVec = ccp.localAnchor2;
                  var r2X = tMat.col1.x * tVec.x + tMat.col2.x * tVec.y;
                  var r2Y = tMat.col1.y * tVec.x + tMat.col2.y * tVec.y;

                  //b1.m_angularVelocity -= invI1 * b2Math.b2CrossVV(r1, P);
                  b1.m_angularVelocity -= invI1 * (r1X * PY - r1Y * PX);
                  //b1.m_linearVelocity.Subtract( b2Math.MulFV(invMass1, P) );
                  b1.m_linearVelocity.x -= invMass1 * PX;
                  b1.m_linearVelocity.y -= invMass1 * PY;
                  //b2.m_angularVelocity += invI2 * b2Math.b2CrossVV(r2, P);
                  b2.m_angularVelocity += invI2 * (r2X * PY - r2Y * PX);
                  //b2.m_linearVelocity.Add( b2Math.MulFV(invMass2, P) );
                  b2.m_linearVelocity.x += invMass2 * PX;
                  b2.m_linearVelocity.y += invMass2 * PY;

                  ccp.positionImpulse = 0.0;
               }
            }
            else{
               tCount = c.pointCount;
               for (j = 0; j < tCount; ++j)
               {
                  var ccp2 = c.points[ j ];
                  ccp2.normalImpulse = 0.0;
                  ccp2.tangentImpulse = 0.0;

                  ccp2.positionImpulse = 0.0;
               }
            }
         }
      },
      
      SolveVelocityConstraints: function() {
         var j = 0;
         var ccp;
         var r1X;
         var r1Y;
         var r2X;
         var r2Y;
         var dvX;
         var dvY;
         var lambda;
         var newImpulse;
         var PX;
         var PY;

         var tMat;
         var tVec;

         for (var i = 0; i < this.m_constraintCount; ++i)
         {
            var c = this.m_constraints[ i ];
            var b1 = c.body1;
            var b2 = c.body2;
            var b1_angularVelocity = b1.m_angularVelocity;
            var b1_linearVelocity = b1.m_linearVelocity;
            var b2_angularVelocity = b2.m_angularVelocity;
            var b2_linearVelocity = b2.m_linearVelocity;

            var invMass1 = b1.m_invMass;
            var invI1 = b1.m_invI;
            var invMass2 = b2.m_invMass;
            var invI2 = b2.m_invI;
            //var normal = new b2Vec2(c.normal.x, c.normal.y);
            var normalX = c.normal.x;
            var normalY = c.normal.y;
            //var tangent = b2Math.b2CrossVF(normal, 1.0);
            var tangentX = normalY;
            var tangentY = -normalX;

            // Solver normal constraints
            var tCount = c.pointCount;
            for (j = 0; j < tCount; ++j)
            {
               ccp = c.points[ j ];

               //r1 = b2Math.b2MulMV(b1.m_R, ccp.localAnchor1);
               tMat = b1.m_R;
               tVec = ccp.localAnchor1;
               r1X = tMat.col1.x * tVec.x + tMat.col2.x * tVec.y
               r1Y = tMat.col1.y * tVec.x + tMat.col2.y * tVec.y
               //r2 = b2Math.b2MulMV(b2.m_R, ccp.localAnchor2);
               tMat = b2.m_R;
               tVec = ccp.localAnchor2;
               r2X = tMat.col1.x * tVec.x + tMat.col2.x * tVec.y
               r2Y = tMat.col1.y * tVec.x + tMat.col2.y * tVec.y

               // Relative velocity at contact
               //var dv = b2Math.SubtractVV( b2Math.AddVV( b2.m_linearVelocity, b2Math.b2CrossFV(b2.m_angularVelocity, r2)), b2Math.SubtractVV(b1.m_linearVelocity, b2Math.b2CrossFV(b1.m_angularVelocity, r1)));
               //dv = b2Math.SubtractVV(b2Math.SubtractVV( b2Math.AddVV( b2.m_linearVelocity, b2Math.b2CrossFV(b2.m_angularVelocity, r2)), b1.m_linearVelocity), b2Math.b2CrossFV(b1.m_angularVelocity, r1));
               dvX = b2_linearVelocity.x + (-b2_angularVelocity * r2Y) - b1_linearVelocity.x - (-b1_angularVelocity * r1Y);
               dvY = b2_linearVelocity.y + (b2_angularVelocity * r2X) - b1_linearVelocity.y - (b1_angularVelocity * r1X);

               // Compute normal impulse
               //var vn = b2Math.b2Dot(dv, normal);
               var vn = dvX * normalX + dvY * normalY;
               lambda = -ccp.normalMass * (vn - ccp.velocityBias);

               // b2Clamp the accumulated impulse
               newImpulse = b2Math.b2Max(ccp.normalImpulse + lambda, 0.0);
               lambda = newImpulse - ccp.normalImpulse;

               // Apply contact impulse
               //P = b2Math.MulFV(lambda, normal);
               PX = lambda * normalX;
               PY = lambda * normalY;

               //b1.m_linearVelocity.Subtract( b2Math.MulFV( invMass1, P ) );
               b1_linearVelocity.x -= invMass1 * PX;
               b1_linearVelocity.y -= invMass1 * PY;
               b1_angularVelocity -= invI1 * (r1X * PY - r1Y * PX);

               //b2.m_linearVelocity.Add( b2Math.MulFV( invMass2, P ) );
               b2_linearVelocity.x += invMass2 * PX;
               b2_linearVelocity.y += invMass2 * PY;
               b2_angularVelocity += invI2 * (r2X * PY - r2Y * PX);

               ccp.normalImpulse = newImpulse;



               // MOVED FROM BELOW
               // Relative velocity at contact
               //var dv = b2.m_linearVelocity + b2Cross(b2.m_angularVelocity, r2) - b1.m_linearVelocity - b2Cross(b1.m_angularVelocity, r1);
               //dv =  b2Math.SubtractVV(b2Math.SubtractVV(b2Math.AddVV(b2.m_linearVelocity, b2Math.b2CrossFV(b2.m_angularVelocity, r2)), b1.m_linearVelocity), b2Math.b2CrossFV(b1.m_angularVelocity, r1));
               dvX = b2_linearVelocity.x + (-b2_angularVelocity * r2Y) - b1_linearVelocity.x - (-b1_angularVelocity * r1Y);
               dvY = b2_linearVelocity.y + (b2_angularVelocity * r2X) - b1_linearVelocity.y - (b1_angularVelocity * r1X);

               // Compute tangent impulse
               var vt = dvX*tangentX + dvY*tangentY;
               lambda = ccp.tangentMass * (-vt);

               // b2Clamp the accumulated impulse
               var maxFriction = c.friction * ccp.normalImpulse;
               newImpulse = b2Math.b2Clamp(ccp.tangentImpulse + lambda, -maxFriction, maxFriction);
               lambda = newImpulse - ccp.tangentImpulse;

               // Apply contact impulse
               //P = b2Math.MulFV(lambda, tangent);
               PX = lambda * tangentX;
               PY = lambda * tangentY;

               //b1.m_linearVelocity.Subtract( b2Math.MulFV( invMass1, P ) );
               b1_linearVelocity.x -= invMass1 * PX;
               b1_linearVelocity.y -= invMass1 * PY;
               b1_angularVelocity -= invI1 * (r1X * PY - r1Y * PX);

               //b2.m_linearVelocity.Add( b2Math.MulFV( invMass2, P ) );
               b2_linearVelocity.x += invMass2 * PX;
               b2_linearVelocity.y += invMass2 * PY;
               b2_angularVelocity += invI2 * (r2X * PY - r2Y * PX);

               ccp.tangentImpulse = newImpulse;
            }



            // Solver tangent constraints
            // MOVED ABOVE FOR EFFICIENCY
            /*for (j = 0; j < tCount; ++j)
            {
               ccp = c.points[ j ];

               //r1 = b2Math.b2MulMV(b1.m_R, ccp.localAnchor1);
               tMat = b1.m_R;
               tVec = ccp.localAnchor1;
               r1X = tMat.col1.x * tVec.x + tMat.col2.x * tVec.y
               r1Y = tMat.col1.y * tVec.x + tMat.col2.y * tVec.y
               //r2 = b2Math.b2MulMV(b2.m_R, ccp.localAnchor2);
               tMat = b2.m_R;
               tVec = ccp.localAnchor2;
               r2X = tMat.col1.x * tVec.x + tMat.col2.x * tVec.y
               r2Y = tMat.col1.y * tVec.x + tMat.col2.y * tVec.y

               // Relative velocity at contact
               //var dv = b2.m_linearVelocity + b2Cross(b2.m_angularVelocity, r2) - b1.m_linearVelocity - b2Cross(b1.m_angularVelocity, r1);
               //dv =  b2Math.SubtractVV(b2Math.SubtractVV(b2Math.AddVV(b2.m_linearVelocity, b2Math.b2CrossFV(b2.m_angularVelocity, r2)), b1.m_linearVelocity), b2Math.b2CrossFV(b1.m_angularVelocity, r1));
               dvX = b2_linearVelocity.x + (-b2_angularVelocity * r2Y) - b1_linearVelocity.x - (-b1_angularVelocity * r1Y);
               dvY = b2_linearVelocity.y + (b2_angularVelocity * r2X) - b1_linearVelocity.y - (b1_angularVelocity * r1X);

               // Compute tangent impulse
               var vt = dvX*tangentX + dvY*tangentY;
               lambda = ccp.tangentMass * (-vt);

               // b2Clamp the accumulated impulse
               var maxFriction = c.friction * ccp.normalImpulse;
               newImpulse = b2Math.b2Clamp(ccp.tangentImpulse + lambda, -maxFriction, maxFriction);
               lambda = newImpulse - ccp.tangentImpulse;

               // Apply contact impulse
               //P = b2Math.MulFV(lambda, tangent);
               PX = lambda * tangentX;
               PY = lambda * tangentY;

               //b1.m_linearVelocity.Subtract( b2Math.MulFV( invMass1, P ) );
               b1_linearVelocity.x -= invMass1 * PX;
               b1_linearVelocity.y -= invMass1 * PY;
               b1_angularVelocity -= invI1 * (r1X * PY - r1Y * PX);

               //b2.m_linearVelocity.Add( b2Math.MulFV( invMass2, P ) );
               b2_linearVelocity.x += invMass2 * PX;
               b2_linearVelocity.y += invMass2 * PY;
               b2_angularVelocity += invI2 * (r2X * PY - r2Y * PX);

               ccp.tangentImpulse = newImpulse;
            }*/

            // Update angular velocity
            b1.m_angularVelocity = b1_angularVelocity;
            b2.m_angularVelocity = b2_angularVelocity;
         }
      },
      
      SolvePositionConstraints: function(beta) {
         var minSeparation = 0.0;

         var tMat;
         var tVec;

         for (var i = 0; i < this.m_constraintCount; ++i)
         {
            var c = this.m_constraints[ i ];
            var b1 = c.body1;
            var b2 = c.body2;
            var b1_position = b1.m_position;
            var b1_rotation = b1.m_rotation;
            var b2_position = b2.m_position;
            var b2_rotation = b2.m_rotation;

            var invMass1 = b1.m_invMass;
            var invI1 = b1.m_invI;
            var invMass2 = b2.m_invMass;
            var invI2 = b2.m_invI;
            //var normal = new b2Vec2(c.normal.x, c.normal.y);
            var normalX = c.normal.x;
            var normalY = c.normal.y;
            //var tangent = b2Math.b2CrossVF(normal, 1.0);
            var tangentX = normalY;
            var tangentY = -normalX;

            // Solver normal constraints
            var tCount = c.pointCount;
            for (var j = 0; j < tCount; ++j)
            {
               var ccp = c.points[ j ];

               //r1 = b2Math.b2MulMV(b1.m_R, ccp.localAnchor1);
               tMat = b1.m_R;
               tVec = ccp.localAnchor1;
               var r1X = tMat.col1.x * tVec.x + tMat.col2.x * tVec.y
               var r1Y = tMat.col1.y * tVec.x + tMat.col2.y * tVec.y
               //r2 = b2Math.b2MulMV(b2.m_R, ccp.localAnchor2);
               tMat = b2.m_R;
               tVec = ccp.localAnchor2;
               var r2X = tMat.col1.x * tVec.x + tMat.col2.x * tVec.y
               var r2Y = tMat.col1.y * tVec.x + tMat.col2.y * tVec.y

               //var p1 = b2Math.AddVV(b1.m_position, r1);
               var p1X = b1_position.x + r1X;
               var p1Y = b1_position.y + r1Y;

               //var p2 = b2Math.AddVV(b2.m_position, r2);
               var p2X = b2_position.x + r2X;
               var p2Y = b2_position.y + r2Y;

               //var dp = b2Math.SubtractVV(p2, p1);
               var dpX = p2X - p1X;
               var dpY = p2Y - p1Y;

               // Approximate the current separation.
               //var separation = b2Math.b2Dot(dp, normal) + ccp.separation;
               var separation = (dpX*normalX + dpY*normalY) + ccp.separation;

               // Track max constraint error.
               minSeparation = b2Math.b2Min(minSeparation, separation);

               // Prevent large corrections and allow slop.
               var C = beta * b2Math.b2Clamp(separation + b2Settings.b2_linearSlop, -b2Settings.b2_maxLinearCorrection, 0.0);

               // Compute normal impulse
               var dImpulse = -ccp.normalMass * C;

               // b2Clamp the accumulated impulse
               var impulse0 = ccp.positionImpulse;
               ccp.positionImpulse = b2Math.b2Max(impulse0 + dImpulse, 0.0);
               dImpulse = ccp.positionImpulse - impulse0;

               //var impulse = b2Math.MulFV( dImpulse, normal );
               var impulseX = dImpulse * normalX;
               var impulseY = dImpulse * normalY;

               //b1.m_position.Subtract( b2Math.MulFV( invMass1, impulse ) );
               b1_position.x -= invMass1 * impulseX;
               b1_position.y -= invMass1 * impulseY;
               b1_rotation -= invI1 * (r1X * impulseY - r1Y * impulseX);
               b1.m_R.Set(b1_rotation);

               //b2.m_position.Add( b2Math.MulFV( invMass2, impulse ) );
               b2_position.x += invMass2 * impulseX;
               b2_position.y += invMass2 * impulseY;
               b2_rotation += invI2 * (r2X * impulseY - r2Y * impulseX);
               b2.m_R.Set(b2_rotation);
            }
            // Update body rotations
            b1.m_rotation = b1_rotation;
            b2.m_rotation = b2_rotation;
         }

         return minSeparation >= -b2Settings.b2_linearSlop;
      },
      
      PostSolve: function() {
         for (var i = 0; i < this.m_constraintCount; ++i)
         {
            var c = this.m_constraints[ i ];
            var m = c.manifold;

            for (var j = 0; j < c.pointCount; ++j)
            {
               var mPoint = m.points[j];
               var cPoint = c.points[j];
               mPoint.normalImpulse = cPoint.normalImpulse;
               mPoint.tangentImpulse = cPoint.tangentImpulse;
            }
         }
      }
      
      
   });
   
   return b2ContactSolver;

});
